#include <iostream>
#include <vector>
#include <algorithm>
#include <unordered_set>

class Solution {
private:
    std::unordered_set<std::string> seen;
    void backrack(int n,std::string& s ){
        if(n == 0)
            return;
        

    }
public:
    std::vector<std::string> generateParenthesis(int n) {
        std::string s = "()";

    }
};




int main(){


    return 0;
}
